Not only is there unpredictable diversity among lots of fetal bovine serum, but the dwindling supply and skyrocketing prices are negatively impacting the cell culture industry in many ways. The cost per liter of cell culture media has increased significantly, which is directly related the amount of FBS used. Zap-SR, a supplement that is well defined and completely animal-free, is able to counteract these effects and allow for significantly decreased cost per liter of media, while maintaining cell growth and performance consistent with 10% FBS. While Zap-SR is able to reduce serum by up to 90% in a wide variety of cell types, the data presented here aims to show the usefulness of Zap-SR in reducing serum in cell lines commonly used for virus production.
In our last article, “Zap-SR Utility in Expanding Cells Critical in Virus Production”, we showed the efficacy of Zap-SR in propagating VERO cells in 6-well plates with an 80% reduction in FBS. While this data is significant, it prompted further investigation of additional cell lines and culture vessels to allow for a better understanding of the impact of Zap-SR on reducing serum in cells relevant for virus production. Here, we look at reduced FBS concentrations in expanding VERO in 150 mL spinner culture vessels. Our future experiments will show data on Zap-SR’s ability to reduce serum in other commonly used virus production cell lines, including MRC-5 and Wi38.
To represent more industry-relevant expansion methods, Zap-SR-supplemented cultures were compared to 10% FBS supplementation in the microcarrier-based expansion of VERO cells in 150mL spinner flasks. To do this, low passage VERO cells were thawed directly into EMEM + 2mM Glutamine supplemented with either 10% FBS or 2% FBS +/- 1x Zap-SR and expanded from a single T-75 to three T-150 flasks over 14 days. At day 14 of the seed train, the cells were harvested and seeded into 150mL spinner flasks containing 10 cm2 /mL plastic microcarriers. Starting at day 2, spinners were sampled every day in order to monitor culture pH (maintained at 6.8) and glucose levels (maintained at 1.5 g/L) as well as to determine VERO cell density. The cell density data showed that Zap-SR efficiently rescues VERO cell growth on 150 mL spinners in the presence of 2% FBS to levels comparable to 10% FBS (Figure 1, below).
Future studies will focus on additional relevant cell lines, as well as the translation of this preliminary data to the production of specific virus strains for vector and vaccine applications. However, this data implies several benefits that come from the incorporation of a well-defined, animal-free component like Zap-SR into cell culture protocols. Not only does this allow for maintained cell growth, as shown here, but using less serum will cause less variability and create significant cost savings.